30 Edward F. Malone. 



of various types of motor cells), but he tvill actttaUy reconstruct the 

 greater portion of the entire complex of cell function upon the basis of 

 the presence in the cell of certain groups of histological characters the 

 meaning of each of which has been determined independently in differ- 

 ent cells. A beginning has already been made in that we are able to dis- 

 sociate in motor cells the characteristic structure (corresponding to the 

 motor activity) and the cell size (corresponding to the spheres of 

 influence and reception of the cell) ; these two dissociated elements of 

 cell character may be employed independently in examining any type of 

 cell in the entire nervous system. Such results can be accomplished 

 only through work which demands the exercise of the greatest critical 

 ability, but that they will be attained I am firmly convinced. 



It is evident that no such results are yet possible in the case of the 

 hypothalamus, since no infonnation is available concerning the func- 

 tions of any of its cell groups; I have been comixdled therefore to 

 draw very general conclusions as to the nearness of functional relation- 

 ship between different cell groups, since these conclusions could at 

 present be based merely upon greater or lesser resemblance of cell type. 

 One conclusion as to the function of these cell groups is, however, 

 possible. The basal optic ganglion, the nuclei tuberis laterales, the 

 nucleus paraventricularis hypothalami and the nucleus tubero-mammil- 

 laris are composed of cells whose histological character indicates that 

 they are not efferent, but are concerned in receiving and correlating 

 incoming impidses; these cells do not possess the relatively large, dis- 

 crete Nissl bodies characteristic of efferent cells. Moreover (as sug- 

 gested by Dr. Donaldson) the small size of such cells as those of the 

 nuclei tuberis laterales would seem to indicate that the connections of 

 these cells were less extensive than those of the cells of the other three 

 nuclei. But now that these various cell groups have been described 

 experimental workers will be in a position to attack the problems 

 involving the connections and general functional significance of each 

 of these cell groups, realizing that differences of cell t}T)e in different 

 cell groups cannot be ignored, since such differences, as in every- portion 

 of the organism, correspond to differences in cell function ; we may then 

 expect results in this region upon which may be based in turn the con- 

 structive neuro-histology outlined above. 



To those who prefer to employ several different histological methods 

 I shall point out the fact that the Nissl method as employed by me 

 brings out very clearly the differences and similarities of cell type, and 



